Electric vehicles may run on varying road conditions. Battery capacity may be of limited use if the battery does not deliver the stored energy effectively. The battery may need low internal resistance to enhance efficiency. Because cold may increase resistance battery of the electric vehicles may perform poorly at low temperatures. To provide extra run time, heating circuitry may be employed to lower the internal resistance of the battery.
FIG. 1 is a schematic diagram of the electric vehicle running control system of the prior art. As shown in FIG. 1, a heating circuit F may be connected with an in-vehicle battery E. By controlling energy flowing between the in-vehicle battery E and the heating circuit F temperature at which the battery performs may increase thus improving charge and discharge rate performance of the in-vehicle battery E.
However, if the heating circuit F is working while the electric vehicle is running, a load capacitor C may supply power to load R. In this manner, the heating circuit F and the load capacitor C may work simultaneously which may cause the voltage of the in-vehicle battery E to fluctuate violently (even to become a negative value). The load R may affect performance of the heating circuit. FIG. 2 shows schematic waveform generated by the heating circuit F and the load capacitor C. VF is a voltage of the heating circuit F. VC is an output voltage of the load capacitor C.